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What might happen if I receive flight instruction in a plane with an airworthiness deficiency?
Let's say I were to a day VFR flight with a new instructor, in hopes of eventually pursuing Sport Pilot - Airplane privileges (U.S.A.)
During the flight, I notice the plane has a minor airworthiness problem. It doesn't affect the safety of the flight, but something required is missing. The magnetic compass, for example, is loose in the glove box instead of mounted on the instrument panel. I bring it to the instructor's attention, he downplays its significance and says he plans to get it fixed in a few weeks.
The flight goes otherwise well. The instructor fills out & signs my logbook in the usual way.
Is this legal instruction time? If this instructor were to get in trouble over instructing in an un-airworthy plane, could that void those instruction hours' applicability towards the sport pilot hour requirement?
(and the more subjective question: practically, how worried should I be over something like a missing compasss? Is it really as minor as I think? Anything I should be looking more closely for before I fly again with him?)

You might be interested in What about hours flown solo without a student pilot certificate?

I don't know about the legality, and certainly not in the US, which is why this is not an answer, but even though it doesn't see a lot of use in VFR/VMC, a compass is still awfully handy at times. Certainly I've been asked by the instructor to make a 180° turn on occasion; even a plain old magnetic compass sure makes it a lot easier to confirm that you've made a 180° turn and not, say, 160° or 200°.

The ability to actually confirm that you've made a 180° turn (plus or minus a small margin of error) is awfully useful if you ever somehow find yourself in IMC, since even without an artificial horizon, you can just focus on your magnetic heading, vertical speed and to some extent your airspeed, and do your best to ignore your other senses.

According to 14 CFR 61.51(j), the aircraft requirements for logging flight time are:

(j) Aircraft requirements for logging flight time. For a person to log flight time, the time must be acquired in an aircraft that is identified as an aircraft under § 61.5(b), and is -

(1) An aircraft of U.S. registry with either a standard or special airworthiness certificate;

[or a foreign aircraft, a military aircraft, or a public aircraft, subject to caveats.]

So, as far as logging flight time goes, the aircraft is only required to be of US registry and have a standard or special airworthiness certificate; it's not required to actually be airworthy. (That doesn't mean that it's legal to fly an aircraft that's not airworthy; but if you do fly it, then you can log the time.)
(The above-quoted paragraph, 14 CFR 61.51(j), is why you can't log time in a Part 103 ultralight. It's legally impossible for a Part 103 ultralight to have an airworthiness certificate.)

if it's not legal to fly, I wonder if that wouldn't implicitly void any paragraph that follows...

It can’t void the time, but if an Inspector ever caught a CFI doing something like that, he’s in big trouble.  And more importantly, that CFI should know better than to do something like that in front of a student.

Or even if a student isn't there....


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What does "203" mean?
In Top Gun (1986), Cougar, who is piloting a jet, speaks to a radar operator on radio
about unknown aircraft:

Cougar: Mustang. Mustang, this is Ghost Rider, 203. I've got him
inbound, bogey heading 270. We're at ten miles, 900 knots closure.
Radar Operator: Ghost Rider, take Angels ten left, 30.

What does "203" mean?

It would help if you could point out in the timeline of the movie, where the dialogue happens. (I believe this is about 5:20 into this movie)

Don't assume that Hollywood scripts necessarily correspond to reality in details like this. Sometimes they do, sometimes they don't. Sorting out the script writer's misunderstandings & inconsistencies isn't really on-topic on Av.SE.

@RalphJ how come is this sort of question not on-topic here? It seems the "203" was at least somewhat legit rt phraseology. The purpose of the question is to find out what 203 means. Had it been total bogus, stating that would have been a good answer. Many questions here start off on false assumptions, that does not make them bad questions.

@RalphJ Hollywood scripts don't necessarily correspond to reality in much bigger things either, but Top Gun was filmed with Navy cooperation, so the chance it does match is much higher in its case. After all the scenes were filmed with actual Navy aircraft flown by Navy pilots.

Military flights use the nose numbers during some portions of flight. Cougar and Merlin fly nose #203.
Screenshot from about 9:40 in Top Gun.

From airport freak

Military flights often use more than one call-sign during a flight. Administrative call-signs are used with air traffic control facilities similar to those of commercial operators. e.g. Navy Alpha-Golf-Two-One, Reach-Three-One-Seven-Niner Two.

Tactical call-signs are used during tactical portions of a flight, and they often indicate the mission of the flight and/or an aircraft's position in a formation.

For example, Canadian Air Force 442 Rescue Squadron, based at Comox, British Columbia uses the call-sign "Snake 90x" depending on the tail number of the helicopter: 901, 902, etc. When tasked on a search and rescue (SAR) mission, however, the aircraft call-sign becomes "Rescue 90x".

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What does "with information Alpha" mean?
In Top Gun Maverick (2022), Lt Pete Maverick speaks on comm:

Lt Pete Maverick: Tower, this is Darkstar. We are taxiing with
information Alpha.
Traffic Controller: Darkstar, you are clear to taxi.

What does "with information Alpha" mean?

Any ATC is going to reprimand Maverick for saying "we are taxiing" rather than "request permission to taxi". Although this is pretty well down the long list of safety violations that Maverick has committed in the space of two movies.

When contacting ATC it's important that they understand that you are aware of current conditions on the field.  This information is provided by the Automatic Terminal Information System (ATIS).  Each version of the ATIS information is given a letter code, and that letter increments whenever the weather report has changed, etc.
"with information Alpha" means when he last listened to the ATIS it was giving out Information A.  This means ATC knows if his information is current or not, and doesn't have to give him weather information as long as it is.
If B ("Bravo") was current, instead, Ground/Tower might have responded with "DARKSTAR, Bravo now current, wind (magnetic heading) at (knots), altimeter (barometric pressure)..." and then given taxi instructions.

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What does "Get a bearing on" mean?
In Top Gun (1986), a flight got hit by a missile:

Airboss: Get a bearing on Hollywood and Wolfman
and launch the rescue helicopter immediately.

What does "Get a bearing on" mean?

Just another word for Direction to...

It means to obtain a magnetic bearing from the ship to the location where the survivors ejected in order to get the helicopter flying in the correct direction expeditiously.
This would entail plotting a point that is 090 degrees for 20 miles from the "bullseye" briefed for that mission, marking that spot, and plotting a bearing line from the ship to that point.
See the answer to this question to understand the second paragraph above:  "090 for 20"


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How close are we to replacing pilots with computers?
Recently someone on another thread recommended the following video:
Andrew Godwin - What can programmers learn from pilots? - PyCon 2015
where the speaker, at about ~3:14, talking about pilots mentions:

not to the point where we can replace them with computers, because we're not there yet

which got me thinking:

How close are we to replacing pilots with computers? (like totally)

Technologically - a very long way off. Politically -even further! I doubt it'll happen in any meaningful way in my lifetime, personally.

For cargo flight, I woul'dnt be so sure.

Several businesses are working on autonomous aircraft including passenger-carrying aircraft. One is Astraea

I wouldn't trust any computer to fly my airplane. Most likely their will be unmanned drones in the future, but I don't think a computer controlled aircraft will ever happen

In principle, an autonomous combat aircraft capable of carrying out air to air and ground attack missions is technically feasible, and could in fact be produced using mainly existing components from other systems such as cruise missiles (for the navigation system) and smart munitions (for the target identification systems and armament).

As a person that "tries to replace pilots with computers" I personally say: not even close.

The processing power (certified for flight, not the latest pentium sitting under your desk) is too behind, in particular concerning the point here below.
Synthetic vision is still extremely lacking. This is currently the biggest hurdle to overcome. While pilots can look out of the windows and assess the situation (with some limits, admittedly), computers still have several problems with it, starting from a general lack of cameras and going all the way to the daunting level of processing power required.
Ability to adapt is still a long way to come. Computers are "fundamentally stupid", they do what they are told (programmed) to do, they are not capable of adapting to an unforeseen (and never experienced before) emergency. There are several people working in machine learning and the field has advanced significantly in the latest years, but good luck certifying those programs.

Google has yet to buy Boeing or Airbus. This is a matter of time.

@mins google is not exempt from certification

Nor is Google exempt from physics

to whomever has downvoted: care to explain?

A lot of people seem to assume that a tactical UCAV would necessarily have to replicate every capability of the manned multi-role fighter to be viable, when the real question is one of how much capability it needs to have in order to be cost-effective.

@J.Southworth what in the question or my answer made you believe we were talking about "tactical UCAV"s?

How close are we to replacing pilots with computers?

In some ways, this has already happened in some limited areas.
Flight Engineers and Navigators
As a precursor to replacing pilots, we have already replaced non-pilot crew on the flight deck. The flight engineer role has been replaced largely by computerized engine systems.
A significant problem for the remaining pilots can be maintaining their skills during their time in the cockpit when they spend long hours mostly monitoring systems rather than doing hands-on piloting.
I suspect, a lot of what commercial and military pilots do boils down to issuing commands to computers, rather than manually (if indirectly) moving control surfaces.
Bomber pilots
In the first gulf war, 297 missions were flown by autonomous aircraft. Many explosive payloads were delivered to targets by small aircraft that flew hundreds of km. These navigated and flew without any on-board or remote human pilot controlling them. Cruise missiles.
The alternative would presumably have been greater numbers of human pilots in conventional bombers dropping smart bombs over the target.
Ground attack pilots
Some jobs that would have been carried out by a pilot inside a ground-attack aircraft are now carried out by a UCAV with a remote pilot. These UCAVs have increasing amounts of autonomy. Some are intended to have full autonomy. It isn't hard to envisage a not too distant scenario where the main human interaction with the aircraft is not piloting it, but authorizing firing of weapons.
Helicopter pilots
Jobs like power-line inspection are, in some remote areas, mostly carried out from helicopters with human pilots but we seem to be on the brink of replacing some of those pilots with drones. That seems a few technically short steps from using autonomous drones. The main time-consuming barrier is probably regulatory change.
Currently, to operate a drone for this purpose, you don't need to be a licensed pilot. Is such a drone operator a pilot. Have they replaced one?

(like totally)

As others have answered, nowhere near.

In technological terms the cruise missile is the closest relative to the autonomous UCAV.

This is a complex question and one that involves both a technical aspect as well as a legal aspect.
From one standpoint there is nothing stopping the FAA from requiring that a human pilot remain in the plane should anything go wrong (or simply to create jobs). Lobbying power should not be underestimated here, there are lots of pilots (and a union behind them) that would be out of work.
But lets talk machine take over for a minute. In some regards parts of the systems do exist. Obviously autopilot to an extent can fly a plane but this generally involves some human interaction and generally holds speed/altitude/heading a change in any one of those may require physical control changes. In a similar vain auto-land systems do exist and they do work. HOWEVER they are complex to set up and require human interaction to currently be used. As far as I know there is no automated system that can currently control takeoff (i could be wrong about that though). Do we possess the pieces to assemble a self flying plane, possibly... To do so, and to get it FAA certified is a very big topic.
The other issue that arises is updating the whole ATC system. If you have not been following the news this is already a mess. But lets say you had a plane that had no one flying it. If ATC needed to reroute the plane, or issue a change in course it would need a system to do so. Currently that is handled via a radio and person to person communication. You would need to dispatch some kind of command to the plane via a data link to do it in an automated system. Then again you can automate ATC etc. etc. (lets not go down that road.

A lot of people seem to assume that a tactical UCAV would have to replicate every function of the manned multi-role fighter to be viable. But a UCAV which only had the capability of flying to a pre-determined location, dropping some mines and then returning to a base location might be militarily cost effective. Adding an infrared sensor and smart munitions to enable it to attack armoured vehicles directly would be quite simple.

@J.Southworth why do you think we are talking about "tactical UACV"s?

There was nothing in the original question to indicate that it didn't refer to military aircraft in tactical roles, so I assumed that it did.

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what would happen if we use needle shaped nose in blended wing?
We are using blunt shaped nose in blended wing,instead of blunt,if we use needle shaped nose what would happen ,it reduce shockwave or it produce bow shock?

This question might need more information, such as a context. Are we talking about the X-48 BWB testbed, or some other test aircraft, or an experimental design of yours, or a model aircraft?

The short answer is that a needle-shaped nose would reduce the leading-edge stagnation point of the aircraft, potentially reducing drag at low angles of attack. However, if it's just the nose, there will be additional stagnation points along the leading edge of the fatter wing. You could build a BWB aircraft similar in theory to the SR-71 (in fact the SR-71 was a BWB design in many ways), but there is a tradeoff; the thin leading edge will cause the airfoil to stall at a lower critical AOA, reducing the performance envelope of the aircraft.

This is my experimental design.

Sounds like you should run your experiment, then report back to us!

I assume you talk about the airfoil's nose, not the fuselage nose.
A pointed nose will cause flow separation in subsonic flow if the angle of attack is only slightly different from the angle of the leading edge. This flow separation will mightily increase drag because now no suction peak at the nose will develop. This suction peak is causing what is sometimes called "leading edge thrust" (PDF!). Without it, the aerodynamic forces will act in a direction orthogonal to the wing's surface and not (almost) orthogonal to the flow direction.
In pure supersonic flow the pointed leading edge is superior, because it causes less wave drag. However, it is preferable to sweep the wing such that the flow around the leading edge will stay subsonic even in supersonic flight, precisely because it still allows leading edge thrust to manifest itself.

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(Why) Do airliners travel together sometimes?
While browsing through the planes in FlightRadar (once again), I've noticed that sometimes some airliners from the same airline company seem to travel "together" on long distance flights to destinations located relatively close to each other (Like Finnair from Helsinki to Hong Kong and to Singapore or to different Japanese cities). The planes were separated vertically by about 2000ft but otherwise quite close to each other. Is there any advantage to this or a good reason? Or is this a pure coincidence?

As you point out in a comment, this is more about why the flights are all dispatched in a small time window. And my suggestion is this is because it's a convenient departure time for customers (or convenient arrival times), and this may improve the employee productivity.

They do this to allow convenient transfer times for passengers at major hubs (in this specific case, Helsinki). In the hours up to the departures of these long range flights, many short- and medium range feeder flights will arrive at Helsinki, with a lot of passengers who are transferring to the long range flights. It basically enables them to operate an efficient spoke-hub model.
Looking at flight schedules for Helsinki as an example, a lot of transfer passengers from all across Europe will arrive on these flights between 15:00 and 16:00:
Major European arrivals
15:00 Budapest and Berlin
15:05 Barcelona
15:10 Dusseldorf, Frankfurt and Manchester
15:15 Brussels, London and Amsterdam
15:20 Stockholm
15:25 Milan
15:30 Madrid
15:35 München
15:40 Oslo and Nice
15:45 Warsaw and Rome
15:50 Hamburg
15:55 Copenhagen
And will then transfer to the various long distance flights that depart between 17:00 and 17:35:
Long distance departures
17:00 AY67 to Guangzhou
17:15 AY73 to Tokyo and AY79 to Nagoya
17:20 AY57 to Shanghai
17:25 AY77 to Osaka
17:30 AY41 to Seoul
17:35 AY89 to Bangkok
Because the long distance departures are bundles so closely, it is possible to create short transfer times from all major European airports to any of the long distance flights.

I do not have inside knowledge of Finnair operations, but I would expect that they have a limited number of staff who speak Japanese, and so logistically running the check in desks for several flights to Japan at the same time allows the airline to schedule checkin staff with appropriate language skills to cover the appropriate flights.
There are also restrictions at both Helsinki and in many Japanese airports that restrict night operations and aircraft on the ground overnight do not earn the airline money.  As a result, there is a limited range of flight times that ensure that the aircraft are operating continually.

It is just coincidence that they are close together. The dispatchers plan the most efficient routing and it is no surprise that aircraft would follow the same routing.

I understand that various planes would often follow the same airways, but what surprised me here was that they were planes from the same (not so big) airline, coming from the same departure airport at similar time, yet even though thousands of miles away from start, still close together.

So maybe the question is why do the airlines plan the departures to distant, but close close to each other destinations, with a similar departure time. Just looking now over Japan, I see that there are three Finnair planes going to three different Japanese cities, that have all departed in a ten minute timeframe.

Following the same routing is due to how air traffic controllers work and the use of ground based radio beacons in the navigation process.


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Are the military tilted-thrust aircraft in the film Avatar feasible?
As full-scale aircraft or as models / UAVs / drones?  Is anyone working on making these real or are they fundamentally flawed designs, or needing new materials to be invented?

I presume you're talking about the fictional Aerospatiale SA-2 Samson. From that page:

Ducted fan VTOL aircraft have been flown since at least the 1960s. A notable example was the Bell X-22, a quad-ducted fan experimental aircraft built for the US military. It has no relation to the later V-22 Osprey tiltrotor. Though successful, no military aircraft since have used that technology.

The Bell X-22 looked like this:

which has similar overall characteristics to the SA-2 depictions.

They are feasible in as much as the atmosphere on "Pandora" is thicker and the force of gravity is lighter. C.f. Avatar Wiki
This allows for both large winged reptiles (?) and smaller tiltrotors than are possible on our current earth.1

1 There is evidence that our atmosphere was more oxygen-rich in the geologic past and may have been thicker, allowing for similarly large reptiles.

They're feasible anyway - in fact, I've seen scale models of them fly here on Earth. As long as you have enough power, they're certainly controllable.

You do know that when you scale down, that because air molecules don't scale down with you, that your model is operating as if it's in a thicker atmosphere.

Oh my mistake, the V-22 Osprey doesn't work on Earth.... I didn't dispute that a thicker atmosphere would potentially allow a smaller rotor, I disputed the fact that it's ONLY feasible with a thicker atmosphere. Scale physics aren't the important point here, thrust-to-weight is, and that's achievable at model or "full size" scale here on earth

The osprey is considerably chunkier and less manouverable than the rotorcraft shown.

Yes, but it's working to a different paradigm and presumably different engine technology. The question wasn't "Can we make a SA-2 from Avatar right now" it was "Is an SA-2 FEASIBLE or FATALLY FLAWED" - it IS feasible and IS NOT fatally flawed. You could, with a big enough research budget and a few years, develop one here on Earth now.

Not sure that the power/thrust ratio would work with ducted fans given our current atmosphere and gravity. It's a matter of physics, not just budgets. We're now moving out of aviation and into scifi.

Yes, they are certainly feasible. In fact, one basically exists already: the V-22 Osprey.
The main difference being that the V-22 has ailerons for roll control and wings for lift in forward flight.
Power isn't a problem, it's just a multirotor helicopter... think Chinook, on a different axis. And control, for the most part, isn't a major issue.

Differential power to the two motors provides Roll control, similar to a quadcopter
Rotating the rotors slightly forward/back and/or something similar to a cyclic on a conventional helicopter allows (similar to the Osprey tiltrotor):

Forward/reverse flight (if tilted together)
Yaw control (if tilted in opposing directions... think tank tracks

If attached in away that they can be angled up/down, pivoting on the attachment to the fuselage, the vehicle can "strafe" (ie lateral sideways movement)
Pitch when in forward/reverse flight is provided by the tail stabilisers. In the hover it could presumably be controlled to some extent by means similar to a conventional helicopter's cyclic, shifting weight, or by an additional small rotor near the tail, if you didn't want to be 100% true to the movie model

Here's a working model, for example. I don't believe there are any full size models, but the Osprey is "close enough" to prove the concept.


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Concorde thrust reversers engaged on parked aircraft, but not all engines?

Am I correct in interpreting this photo as showing one thrust reverser engaged, while the other is open? Do the thrust reversers fall into place on a fully powered down Concorde? Could this be caused by an engine being removed for display? If so which engine was removed?

They might have opened it just for display purposes...

Yes the left (#1) reverser is engaged in this photo. G-AXDN is the British pre-production Concorde and has some differences from the final versions. G-AXDN contained internal clam shell reversers, if the GIF at the bottom of this informational page about G-AXDN is any indicator that external engine reverser may still actuate for show and in this case was simply closed while you were there. This video shows the light up ring that they may have used in the GIF (5:02)
This Concorde also has a droop nose that still works. There is also a fairly active effort going on to restore that airframe to have some of the parts work.


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What are these pipes on an Avro Vulcan?

As you can see above, there are two small pipes next to the main engine exhausts on this Avro Vulcan(the one at Duxford). I'm curious what these pipes are/what they are for. Are they fuel dump pipes? If so why have two right next to each other?

Try http://img204.imageshack.us/img204/3003/avrovulcanb21957mungerf.jpg . I cant find it but it looks interesting.

Streaming point for drag chutes?

Drag chutes sounds plausible, but this photo seems to indicate otherwise: https://shop.photo4me.com/399535/canvas

What's surprising is that there's a cover on one side only: https://www.flickr.com/photos/chris-heal/22128976172

Although it is difficult to say from old photos, the tubes doesn't seem to be visible on the prototype or early Vulcans.
Another Vulcan, XH558 started life as a B2 and are fitted with Olympus 202 engines. Looking at a photo of it there are what appear to be intakes on each engine, as seen here. I don't know what engines the Duxford Vulcan has, but according to Wikipedia the 202 was the definitive version for the Vulcan, with the exception of some aircraft which received the 301. As far as I can tell, one of the features with the 202 was that it had a redesigned oil separator breathing system.
Such features require air inlet as well as an outlet for the vented gases, could this be related to that system?

This give great clues but does not answer the question "what are they?"

Well, they're not for fuel dumping or for drag chutes.  That much at least is ruled out by the 156-element cutaway diagram on pp. 183-186 of P.D. Stemp's "Kites, birds and stuff: Avro Aircraft."
A similar diagram of one of the B.2's Olympus 301 engines might conclusively name these pipes.
This photo from Grace's Guide reveals some peripheral pipes that might give a clue.

... or not. The pipes in the picture terminate at the section after the turbine. There is nothing there that gives a clue as to what the pipes in question are.

It answers the question "what are they not?" but not the actual question "what are they?"

At this point we're all grasping at clues.  Maybe someone has a not-online book on their shelf...

The two thin pipes next to the inner exhaust ports are indeed fuel dumping pipes. the Drogue chute is mounted in the rear of the fuselage directly below the rudder.

The Vulcan had no fuel dump facility, they’re probably fuel vents but it’s been a while since I flew them so. I can’t remember!


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Can you put a propeller on the back of a plane, and have it go forward?
So, I was thinking about how drones work, and I can't figure out how drones with propellers at the rear of the drone can still go forward. I'm not that experienced in aviation so if this is a basic question, I just didn't know the answer.

It's call a pusher propeller configuration. I'll it to the experts to answer authoritatively, but as long as the blade is curved in the right direction it will still propel air backwards and the plane forwards. Related question. Boeing even had a prototype 7J7 in the early '90's (video)

Interesting corollary ... propellers on boats and submersibles perform the same function as a propeller in a plane. Yet, you don't hear people asking why are there no boats with propellers at the front, like in a plane ?!

In addition to all the excellent answers and comments from people who know a lot more than me... the simple answer is yes. The propeller just has to spin the other way. (Or have its blades twisted in the opposite sense.)

Please note, that the direction in which the propeller is moving the airplane is not defined by where it is placed, but why which direction it is rotating in, (and how the blades are angled).

Jet aircraft have the exhaust nozzle at the back - why wouldn't it work with a propeller

Your title and your text ask two different questions: your title asks if a prop can be placed at the rear if a plane, and your text asks how a plane go forward if the prop is at the rear. Please edit one or the other. - Probably you should change the title, as its answer is trivially obvious.

Imagine swimming with your arms vs legs. Either technically works despite one being at the front and the other being at the back.

@ DarthVlader You don't need any changes to the propeller. They may be called pusher propellers but they are more accurately called left-handed propellers. This naming is more related to the conventions associated with the direction of rotation for an engine (usually CCW when facing the engine shaft) when you take an engine and turn it around to face backwards. It's nothing inherent to the propeller aerodynamics.

The answer to the question is "nope".  Things such as this cannot work and therefore are a figment of someone's overly active imagination--  https://en.wikipedia.org/wiki/Kyushu_J7W_Shinden .  (Or maybe the plane was actually secretly designed to go backwards and confuse everyone?  Psych!!!)

Yes, in fact airplanes with pusher propellers were flying before those with tractor propellers:

Photo Credit: Smithsonian Air & Space Magazine

Since our intrepid OP seems rather new to aviation, I'll note that this is one of the original Wright Flyers. The first heavier-than-air craft to make sustained, controlled flight.

It may also be worth noting that the front of the above aircraft is at the left of the photo. The elevator was at the front of the aircraft, and the propellers were at the back. The person is laying forward with their head pointing in the direction of flight.

@GregHewgill Can't imagine there are that many planes where the pilot faces backwards to the direction of flight.  Maybe rear gunners on some military planes, but they're not the pilots.  (I also know the person who controls the midair refueling boom on tanker planes is sometimes called a pilot, but they're not the pilot.)

There are actually some planes that have this setup. Majority of prop driven airplanes use the pulling method, in which the propeller acts like a airfoil (wing) and the propeller itself generates lift which pulls the plane forward. This is also known as the tractor configuration.

But in this case you are talking about a pusher configuration. There are a few planes which have this configuration As seen below.

The Pusher configuration actually works just the same way as the tractor configuration. So the drone that you are referring to works no different from normal planes.
This website talks more about how propellers work.
How propellers work
And this link talks about some of differences and pros and cons
Pusher versus pulling propeller

Pusher's nose fins and fans reminds me of the famed Brabham "fan car" of 1978  https://www.tracksidelegends.com/articles/brabham-f1-fan-car-BT46B  though in the latter case the fan was for enhancing ground-effect of air under the car rather than thrust forward.

@Trunk, that car is very interesting!!!!

@Trunk For another non-flying example, think of airboats, which are propelled by a large fan at the back.  Come to think of it, most powered boats and ships have the propeller(s) at the back, though unlike airboats, they're usually underwater.

@Trunk Jim Hall’s Chaparral 2J predates that car by at least 7 years. https://en.wikipedia.org/wiki/Chaparral_Cars?wprov=sfti1

Yeah. It was nice piece of idea borrowing by Murray. Though at the time no one in F1 said anything other than it being another devilishly clever idea from the ZA genius.

To answer the question in your text (instead of the title):
Suppose you bought a used single-engine airplane with the propeller on the nose and fixed it up. Imagine starting up the engine, the prop spinning, blowing air backward, pulling the plane forward.
Now imagine you have bought the wrong engine. When you start it up, it runs in reverse, the prop spinning in the other direction. What happens? The prop blows air forward, pushing the plane backward.
Obviously this is useless as the plane is not designed to fly backward. You can't even taxi straight.
So you disconnect the plane from the engine, keeping the engine where it is, turn the plane around, and attach the tail to the engine. Now the engine and the plane agree about which direction they should go. You have invented the pusher prop.
Of course, if you want to get the thing to actually fly, you're going to make a lot of changes -- but none of those changes will involve changing the direction the engine is spinning, or changing the direction the plane is pointing.
Instead of spending years of wind tunnel and dangerous flight testing, you can steal plagiarize copy most of those changes from other inventors. You want to look at the Rutan LongEZ, the Anderson Greenwood AG-14, and the Cessna 337 Skymaster, for example.
In every case, the engine is stuck onto the wrong end of the airplane, but that's OK, because the engine spins the wrong way.

EDIT: To help the OP better grasp the concept of how it's possible to put propellers on the back of a plane and help them grasp the concept of how drones with propellers on the back work, it may help just as an initial frame of reference to think of the placement of the propellers on planes as operating similarly, in basic principle, to the main two types of vehicles and cars on the road with regard to those that are driven using front-wheel drive versus rear-wheel drive driven vehicle.
Whereas most modern vehicles in the Western part of the world utilize a front-wheel drive setup that involves having the engine usually being installed in the front of the vehicle and is used to spin the front wheels, whereas the spinning force of the wheels pull the car forward.
Conversely, in a rear-wheel drive model vehicle, the engine is usually found in the back of the vehicle and otherwise is used to spin the rear wheel tires to push the car forward.
Both constructs have their advantages and disadvantages similarly to planes with those designed to have propellers in the front and those designed to have propellers in the back.
The propellers themselves play almost the same exact roles as the wheels on a car where power from the motor engine is used to rotate the propellers which exerts the necessary force of momentum to move forward. In this case, spinning the propeller blades force air to move in a particular direction that is generally coming out from "behind" or "under" the propellers if you looked at them from a top-down view. Others have answeres with links above to learn more about how propeller works but hopefully that helps remove any confusion that may have prevented an better understanding.

Edit Notes
In previous posts, everyone provided great answers already explaining the
difference in propeller systems and it was only in realizing how I had
misperceived the reference to drones that I realized, maybe the OP
has reached the same level of understanding that might seem like second nature to others and before diving in to the details of the physics and technical explanations on how propellers work, I thought it might help the OP better grasp the general concept and ideas rather than what was previously suggested and written below, but otherwise the above edit was added while below is kept simply for posterity.

Although I would've elected to post this as a comment and an answer has already been marked, I don't have the reputation in this community to do so, but to address where your question stems from, with regards to how drones can be propelled forward, they often use propellers differently than your typical airplane. How they use their propellers, or how drones with propellers at the rear of the drone can still go forward, would be better imagined as being similar to how a helicopter can still move forward.
If you're referring to the rear propellers of a drone, I would assume you are referring to the rear propellers in a quadcopter setup. In simple terms, the drone is able to move forward by varying the speed of its front propellers from it's rear propellers. This is why when you see a drone move forward, you will see it begin to tilt forward as it begins to move forward, this is because the rear propellers are spinning faster and producing more thrust from its rear propellers, to create an intended imbalance of sorts, allowing it to lean and begin moving forward; simulating the same sort of forward motion suggested by the concept of "falling forward" when you run (though this terms should not be taken literally).
With a greater thrust pushing air "down" at the rear of the drone, the leaning forward of the drone helps direct the propulsion of the drone and redirects the force of moving air coming "up" (or the force pushing up on the rotor that is pushing air down) to be more at an angle (again, an oversimplification) which pushes the drone to move forward or whichever direction it is leaning towards.
While this is a simplified explanation, if you want a more physics-based answer that dives into the how the propellers work, the direction they spin, and explains things like angular momentum being the rotational equivalent of linear momentum, etc. you may want to check out this site. But, hopefully that helps you imagine or understand how drones can fly forwards, backwards, side to side, even with propellers in the rear.

I thought that OP probably meant drones like the MQ-9, which fly like typical airplanes but have pusher propellers.  Maybe OP can clarify.

nice "comment" (it is too big to fit in a comment)

@Edward ahh you're probably right, that didn't cross my mind at the time and now I feel kind of silly for assuming the former. Though I now do wonder if maybe the OP was just generally curious to learn how lift, thrust, drag, and all that work together but due to a lack in experience, they were only able to propose and form a question that asks about what stirred their curiosity in the first place. At least, that might help me explain why there's one question in the title and another in the text as pointed out by someone else in an earlier comment. And, Phil ikr >_<


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Does Indicated Stall speed increase with altitude (Coffin Corner)?
It is my understanding that Indicated Stall speed is mostly constant with altitude, the one that increases is True Stall Speed. Given that PFD show speed as IAS, how come the yellow speed range increase with altitude?

The yellow arc is not related to stall speed.  I assume you are asking about the top of the yellow, or Vne?

I mean the bottom part, the stall speed,  I undertand why the top would close in creating the top part of the coffin corner but not the bottom one, assuming indicated stall speed remains mostly constant with altitude.

The bottom of the yellow isn’t stall speed either, it should be Vno.  In any case, could it be some PFD specific setting you are observing?  (I.e. values entered in true, displayed as indicated?)

Check this out:  https://aviation.stackexchange.com/questions/65766/why-does-indicated-stall-speed-change?rq=1

I think part of your confusion comes from mis-interpretation of the amber bands on the PFD. The picture you show looks like it is from a Boeing 777, which has the red barber pole and the amber band towards the top of the speed band defined like this:

5 Maximum Speed
Indicates maximum permissible airspeed as limited by the lowest of the
following:

Vmo/Mmo
landing gear placard speed, or
flap placard speed.

6 Maximum Maneuvering Speed
When displayed, indicates maneuver margin to high speed buffet. Bottom
of the bar is the airspeed that provides 1.3 g maneuver capability (or
an alternative approved maneuver capability as preset by maintenance).
Bar may be displayed when operating at high altitude at relatively
high gross weights.
Note: 1.3 g maneuver capability occurs at 40 degrees of bank in level
flight.

(Boeing 777 FCOMv2 - 10.10.3 - Flight Instruments, Displays - Controls and Indicators)
It also has a red barber pole and amber band towards the bottom of the speed band defined like this:

4 Minimum Maneuvering Speed
Indicates maneuver speed margin to stick shaker or low speed buffet.
Top of the bar is the airspeed that provides:

1.3 g maneuver capability to stick shaker with flaps down.
1.3 g maneuver capability to stick shaker or VREF + 80, whichever is less, with flaps up below 20,200 FT.
1.3 g maneuver capability to low speed buffet (or an alternative approved maneuver capability as preset by maintenance), with flaps up
above 20,200 FT.

Displayed with first flap retraction after takeoff.
Note: 1.3 g maneuver capability occurs at 40 degrees of bank in level
flight.
5 Minimum Speed
Indicates the airspeed where stick shaker activates.

(Boeing 777 FCOMv2 - 10.10.5 - Flight Instruments, Displays - Controls and Indicators)
Note that the top of the amber band above 20,200 ft is related to buffeting and not stall speed (near stick shaker activation) or something "preset by maintenance". Therefore, this does not indicate a change in stall speed. Why buffeting becomes the limiting factor at higher Mach number is already explained in this answer.
Having said this, it is also true that indicated stall speed increases with altitude. This is not really significant for smaller GA planes, where to first approximation stall speed will be at a constant IAS. At higher altitudes and at higher Mach numbers, the stall speed will increase for various reasons, which are well explained in this answer.


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Aside from simulated dogfights, do F-22 Raptors actively participate in live fire/target practice using live munitions?
I am aware that the F-22 was developed specifically for the air-to-air superiority role, although it has previously proven its worth for multi-role missions (in performing ground strike missions during Operation Inherent Resolve before F-35 was put into active duty). I was wondering if F-22 Raptors are being used today to test/use their own live munitions for practice/training periodically at ranges or designated areas? To put into simpler terms, do F-22s ever use their M61A2 Vulcan cannon or AAMs for practicing live fire training/operations? I'm not looking for a real detailed answer if this is classified/secret info. Please do not bash me for asking such a odd question regarding a classified aircraft. If there is anyone on this site who has worked with F-22s, please answer if you'd like. Thank you.

Weren't the Chinese balloons over the US shot down by F22's? Nor sure if that counts

@DeltaLima - Yes. That was a regular line aircraft from the 1st Fighter Wing at Langley AFB. NOTE: That was the highest recorded altitude for an air to air kill. 60,000 - 65,000 feet.

@DeltaLima That's not what im asking though. I wanted to know if F-22s are regularly used for live fire/munitions training. The balloon kill was an actual threat that had to be taken out.

Plenty of times.  There are multiple missile shoots annually out of Tyndall Air Force Base, where F-22s or other active duty and reserve Air Force units fire live ammunition at target drones over the warning areas in the Gulf of Mexico.  The United States Navy conducts similar exercises over the Pacific at Pt Mugu, CA.
During the Cold War, United States, Air Force, conducted a biannual gunnery exercise called William Tell out at Tyndall where various units competed in air-to-air live fire exercises for the top spot as Top Gun.
There are a variety of aircraft are utilized for live fire targets, from purpose built drones like the Ryan BMQ-34 Firebee, to retired jet fighters converted into target drones.  Target aircraft are recycled from outdated fighter types in storage in AMARC at Davis-Motham AFB.  They undergo a program of being re-fitted with remote control servos for the flight controls as well as flight termination hardware in case radio contact is lost.  Once so fitted, the aircraft are transported to, maintained and stored out of Tyndall AFB. When missile shoots are scheduled, the target aircraft, marked with orange tail fins and wing tips, are parked on a section of Tyndall’s ramp - aptly named ‘death row’ - and made ready for their final flight.
The only notable difference is that the warhead sections on guided missiles are often removed. This is to maximize the reusability of the target drone in the event a direct hit is not scored.  Target aircraft that are still flyable after a shoot are then flown home to be reused. The ones that don’t make it fly their final approach into Atlantis AFB and begin a new career as a submarine.
On 22nd November 1973 an F-14A launched no less than six AIM-54 Phoenix missiles at six different target drones, resulting in four direct hits, one miss, and one no-test due to an RCS augmentation failure of the drone.  This was perhaps the most elaborate and expensive shoot ever conducted at a missile range.
Gunnery exercises ie shooting at an aerial target using an internal gun or gun pod, have been done in the past. However, it would be cost prohibitive to use a drone for this on most occasions.  Instead, gunnery exercises have utilized an aircraft towing, either a banner target, or a dart like object to be shot at.  It provides a very cheap live target albeit with a minimal risk to the tow aircraft.  In modern times, with better instrumentation, this has been foregone in favor of simply simulated kills using HUD footage and an ACMI pod. Former F/A-18 pilot Trevor "Gonky" Hartsock has described this process for BFM training in the T-45 airplane on his podcast before.

Interesting. I didn't know that Tyndall AFB was still being used after Hurricane Michael hit. Thank you for explaining. I do wonder though, if the use of the M61A2 Vulcan is permitted or not during these missile launch exercises.

They can employ guns against a drone in a live fire exercise, but it’s much more economical to do it other ways. See the additional post above.

In my (40 years ago) US Navy experience, when the warhead sections were removed from missiles those sections were replaced with telemetry modules to gather additional data about the engagement.

Have F-22s fired live missiles in training?
Absolutely. Here, firing AIM-9.
These were almost certainly not with a live warhead, but everything else was 'live'.

https://theaviationgeekclub.com/interesting-video-shows-f-22a-raptor-firing-an-aim-9-sidewinder-while-inverted/
(Fun fact - I know someone who is/was intimately involved with the scheduling software to make these tests happen)

Fun fact - I used to schedule tests on the Eglin AFB range in the late 80's. The VAX-based range scheduling software was universally despised by Test Project Managers. Hopefully it has improved in the last 30 years. The VT-100 user interface was not user friendly.

@Gerry @ WPNSGuy that's awesome! Thank you for sharing, I appreciate the responses and I thank you Gerry for your service.

According to this article in Business Insider the F22s at Eglin AFB participated in a live fire exercise using the AIM-9 back in 2020. The article says for most of the pilots, it was the first time firing the missile. I'm sure similar exercises have happened since, but I didn't see anything more recent doing a quick search.


text:
What exactly is LDI (Landing Direction Indicator), what does it look like, where should it be, how does it work and how do pilots use it?
What exactly is LDI (Landing Direction Indicator), what does it look like, where should it be, how does it work and how do pilots use it?

Thanks for the quick answer, but I need a more explanatory and detailed answer. I have learned that they have different structures in Europe and America without knowing what they do and what they are used for.

This may answer all your questions: What is this radar-like thing?. This is the model used in Turkey, it's not always wind-rotated, it can be manual.

The answer to this question was more appropriate, thank you.


text:
Can you explain what the 2nd caution on the LTAF VOR A chart means?
Can you explain what the 2nd caution on the LTAF VOR A chart means? "2. IF THE AIRCRAFT WILL MAKE A CIRCLING APPROACH VIA RIGHT TURN, ATC SHALL BE INFORMED AS SOON AS POSSIBLE." What exactly does this expression mean? I couldn't understand the use of "right turn" in particular. Because, although our main approach procedure is VOR A approach, is it meant to be described as a "Circling Approach" carried out from the north of the aerodrome? We see that the minimum value is also given as a circling, not a straight-in approach. Is this the 2nd caution written by considering VOR A approach as circling approach, or only the minimum value of VOR A approach is given as circling, and in fact, circling approach and VOR A approach are completely different things? I would appreciate it if you explain clearly by comparing the terms VOR A, circling approach, minimum value, and right turn. Here is the chart:

Have you asked any local pilots or ATC how this is expected to be flown?  Because I'm stumped why you would not be able to land straight ahead on a course of 228.  (although the base question about the warning is clear enough.)

@MichaelHall There is a question on that topic here. There is a 591' obstacle just south of the extended certerline between the MAP and the runway threshold. This prevents a straight-in minimum from being published, but as far as I understand it doesn't prevent the pilot from landing straight-in if they have runway 23 in sight and can land safely.

I got the answer to this question where @Chris mentioned it as 591' height obstacle as stated. But the real problem here is how the VOR A and Circling procedures are separated or applied (right turn).

Ok, then I am unclear what you are asking.  The base question is asking about the meaning of #2, which as Chris points out is obvious.  And per this plate, the VOR A is a circling approach.  There are no straight in minimums, so what do you mean by how are they "separated or applied"?

I guess I couldn't express myself properly due to the language barrier. There are many questions that we need to understand before we can come to a conclusion here. If the approach we call VOR A is a circling approach, is the maneuver called "Right Turn" a maneuver that we will use when applying VOR A, or if the approach we call VOR A is a VOR approach, is the maneuver we call "Right Turn" a circling approach maneuver with a completely different procedure? First we have to decide. Theoretically or practically, is the VOR A approach straight or circling approach?

Is the "Right Turn" term to be used next, the turn maneuver we apply for the circling approach, independent of the VOR A approach when we perform to turn north of the aerodrome while descending at 228°? Or is it that we move away from the VOR, for example on the 060° course, so that the outbound is not 030° (i.e. not from the left of the approach line), that is, from the south of the aerodrome to the right, and we do this by assuming the main approach procedure, VOR A, as a circling?

@pilot162 You're overcomplicating things. A "right turn" is the basic maneuver that you learned on the first day of your PPL training, where you use the ailerons to bank the aircraft so that the right wing is lower than the left wing and the aircraft's course changes to the right.

This is where I think speaking with local pilots and ATC would be most helpful. I think that they cannot publish straight in minimums due to violating obstacle clearance rules. But perhaps as long as you are visual and call it a "circling" you're legal to fly and land straight ahead?

Yes, as you said, this is probably the most logical way. @Chris it's not about the right turn maneuver (of course I know what it means to turn right), it's what procedure we do that maneuver with. The question is whether we should apply the right turn when moving away from the VOR or when approaching the runway with 228°. I apologize if I have misunderstood and complicate matters unnecessarily due to the language I use.

@pilot162 You need to follow the depicted course to the missed approach point. At the missed approach point, you either initiate the missed approach or descend to the aerodrome for landing. Turning off course before the missed approach point is neither allowed nor safe.

So, if we are going to make a circling approach, at which DME or point should we do it at 1200 feet? So we have to turn to the north of the aerodrome with a right turn when we are on the 228° course, right?

For any procedural questions, here or with local pilots or ATC, you should specify the landing runway.

@pilot162 As long as you stay within protected airspace, don't go south of the aerodrome, and don't descend below MDA until you need to to make a normal descent for landing, you can fly it however you like. Note that the 228 course puts you on the upwind leg for 23- if you are landing 23 and the visibility is good enough, you can fly over the aerodrome then turn right crosswind and just fly basically a normal VFR pattern.

It means plainly what it says. A right turn is when you turn to the right. If you are going to make a right turn, you need to tell ATC as soon as possible that you are planning to do that. Since you are not authorized to turn left (as that takes you south of the aerodrome), this means you must notify ATC if you are not going to land straight-in.
Your related question asks why this has no straight-in minimums published. The reason is that there is an obstacle just south of the extended centerline in between the missed approach point and the runway threshold. This prevents straight-in minimums from being published. It does not prevent the pilot from flying straight-in if they have the runway in sight and have sufficient time to make a normal approach for landing.
In other words, this is an approach where they want you to approach runway 23 straight-in, but they can't promise you the obstacle protection that they would need to for a straight-in approach. So they give you circling minimums and ask you to land straight-in if you can.

I'm writing to make sure I understand correctly: The circling approach maneuver we call "Right Turn" is the maneuver we decided to make a circle to land while approaching runway 23 on the 228° course, and because it is prohibited in the south of the aerodrome, we turn right and turn to the north of the aerodrome, right? Because the maneuver in which we turn left and move away from the VOR on the 030° course might also mean the term "Right Turn" if they consider the approach type we call VOR A as a circling approach? (Because the minimum is given as a circling, not a straight-in approach)@Chris

@pilot162 A "right turn" is when you turn to the right. If you turn left, that's a "left turn." For instance, you could overfly the field and then turn right to make right traffic for 23. You have to tell ATC if you're going to do this. Or you can just land straight-in on the 228° course for runway 23 without turning at all. You don't need to tell ATC if you are doing this, implying it's what ATC is assuming you will do. In other words, this is technically a circling approach but it doesn't actually want you to turn unless you need to.

From the 228° course a left turn is prohibited since it takes you south of the aerodrome. A right turn is allowed but you need to inform ATC. But you can also land without turning at all. This would look a lot like a straight-in approach, but because of the obstacles it is legally a circling approach.

Your last comment you added to your answer was exactly the answer I was looking for, thank you. Also, I would like to ask, wouldn't it be possible procedurally if the minimum value of 1200 feet was given as the straight-in approach value (as the name) and the missed approach point was before the obstacle on the approach line exactly at 8 DME? Thus, since 1200 feet is the minimum, a straight-in approach could be applied if there is a runway view before the obstacle at this altitude and at 8DME. (The issue is just not giving the name straight-in approach.) @Chris


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What is the difference between EGT and TIT?
In a gas turbine engine, what is the difference between Exhaust Gas Temperature (EGT) and Turbine Inlet Temperature (TIT)? I assume EGT is the temperature after the gas has transferred power to the turbine. Does that significantly change the temperature? Are they both proportional to engine power output?

Another measurement is the Inter-Turbine Temperature (ITT)

EGT is just that - the temperature of the gas leaving the gas core at the jet pipe.  TIT is the temperature of the gas in the gas generator as it exits the combustors and enters the first high pressure turbine stage.  EGT will be significantly cooler - sometimes by as much as 1500°F! - than the TIT, as the enthalpy or internal and kinetic energy of the working gas is converted into mechanical work by the turbine, reducing the pressure and temperature of the gas flow as it exits each stage of the turbine.  See the Brayton Cycle model for these kinds of heat engines.
Usually the power output for a turboprop or turboshaft is measured as the torque on the power shaft turning either the propeller or rotor transmission.  Thrust on jet engines is usually gauged by the flight crew as N1, or the ratio of the current speed of the fan/LPC/LPT spool to its maximum speed.  This is a bit misleading as the actual thrust the engine generates does not vary linearly with fan speed, but that is the benchmark.
EGT and TIT are not monitored for power output reasons so much as making sure the engine does not exceed its thermodynamic limits.  Too hot a temperature in parts of the gas core will cause serious damage to the engine, requiring major overhaul and/or replacement of the entire engine or subsections.  These temperature limits can exercise limitations on power or thrust settings for the gas turbine during operation to prevent overheating.  On a free turbine turboprop, for instance, your power settings are bounded by both the torque limits of the propeller gearbox and another kind of hot section temperature called the Inter Turbine Temperature (ITT) which is the gas temperature between the high pressure gas generator turbine and the low pressure power turbine.  These limitations cannot be exceeded in order to prevent engine damage and may restrict maximum power settings at both low and high altitudes.

Additionally, it is worth noting that on free-turbine turboprops, N1 (Ng) is also a limiting power setting parameter, and can be the limiting parameter when the compressor section is inefficient and nearing serviceable limits.


text:
Is it possible to open a cabin door inflight?
In recent news here in England was the case of a female passenger on a flight I think London to Antalya, who got a bit out of control, and decided she wanted to leave the airplane and tried to open the cabin door - in mid flight. I couldn't identify the plane, but just an average plane used by holidaymakers.
This would obviously frightening for everyone, but would there be actually any chance that she succeeds? If she was not an average woman but an unusually strong man? If she worked on other flights and had knowledge how to open cabin doors. that the average passenger doesn't have, but no keys etc. that would be needed on that flight?

Almost all airliners have doors that are some form of plug type which have to be moved inward to open, and when the airplane is pressurized, the 8 or so psi of cabin pressure differential will be pushing the door out with, say, 20000+ pounds of force for a door with a surface area of about 2500 square inches.
Even a residual amount of pressure making a couple thousand pounds of force would make the door impossible to open for a normal human, which is why the opening mechanism includes some for of venting to make sure all residual pressure is gone.
To do it in flight, she would have to get the flight crew to fully depressurize the cabin first.
Even on a non-plug door as used on some airliners (CRJs have non-plug main doors) the shear loads on the pins that hold the door in place are so high that you can't move the mechanism that withdraws the pins to open the door, once the plane is pressurized to any significant degree.  It's like the operating lever is bolted in place.

On almost all airliners, as you said the doors are of plug type. But, there's a catch, The emergency exit doors near the wing are not. I've observed this in B737/A320, etc. The door locks of the emergency exits are electronically locked. They unlock only if the aircraft is on ground (Same way the cargo hatch works). If you do find someway to exert enough amount of force, causing the lock to fail then, these doors will open mid-air. Other doors (the main ones) are plug type and are impossible to open due to cabin pressure.

Thanks for fixing "airliners" but the other edits are style edits that  I would normally reject.  I'll leave it as you changed it however.  As to the comment, I'm covered by "almost", plus I was mainly talking about entry/service doors.  Overwing exits are really hatches, since they don't have hinges.

@AtheeshThirumalairajan Are you sure the A320 overwing exits are not of plug type? They have to be moved inwards before they can be thrown out, unlike the 737 ones which open outwards.

Okay, I wrote A320 by mistake and I was unable to edit the comment due to low reputation on this forum.


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Why don't airliners have a navigation GPS as back up in case of a pitot tube malfunction?
Why don't airliners have a navigation GPS as "back up" in case of a pitot tube malfunction? Aeropero 603 and Air France 447 plus many other im sure, could have been saved if these aircrafts would have had a simple Navigation GPS as a plan B. The GPS could have given the pilot the basic information needed to keep flying instead of leaving them confused about what the instruments were showing due to the blocked pitot tubes. having reliable information of ground speed, heading and altitude would have helped the pilots recognize the situation they were in, which was caused by Pitot tubes blockage. Most private pilots now use GPS why not the big airliners?
There is many blogs about why airliners do not have GPS tracking so the planes could be found after a crash, but none talking about why GPS is not use to help prevent some of those crashes.

The pitot tube is not used for ground speed, but for indicated airspeed (and calibrated airspeed when corrected for instrument error, true airspeed when corrected for temperature and pressure). Knowing your groundspeed from a GPS is not going to get you your airspeed, and it's the indicated/calibrated airspeed that is telling you where you are within the flight envelope. The higher you go, the greater the difference between groundspeed and indicated airspeed. At 40,000 feet, you're going to have well over 100 knots difference between ground speed and calibrated airspeed as I remember.

@Terry Very true. The difference will be even larger when you're flying in a 180 mph jet stream. On airliners flying through the Northern polar jet stream, I've seen ground speeds that would have been well over Mach 1 in still air.

To notice as well that GPS belongs to USA army. If an airplane manufacturer wants to sell airplane to country not alligned to USA, it should take care of not having a single failure point due to not availability of GPS. USA already darked Kosovo.

@Trebia "USA already darked Kosovo." That's interesting. Do you have a link for that? It seems like that would be really hard to do for such a small area (relative to the area that the signal from a satellite would hit,) unless, of course you just jammed the frequencies from the ground.

If GPS won't provide airspeed, why not use other methods?

@reirab in response to pressure from the FAA, in 1996, Bill Clinton signed a bill precluding Selective Availability from being used after May 2000. It seems like Trebia's information is about 15 years out of date. Newer GPS Block III satellites (est. launch 2016) supposedly don't even have the feature. Here are some interesting error plots just before and after SA was terminated.

Hmm, actually we already have this question: Could the GPS be used to aid the autopilot with speed?

@HenningMakholm These look like different questions to me. The other one is related, but this question is "why don't airliners have GPS?" (to which the answer is that they do have GPS.)

Airliners do generally have GPS receivers, but GPS doesn't give you the information that's needed in this case.
In AF 447, the primary consequence of the blocked pitot tubes was that the flight envelope protection system couldn't do its job properly and therefore automatically disengaged together with the autopilot. The subsequent crash was caused by the pilots' confusion and failure to realize which consequences this had for the aircraft's reaction to their control inputs.
However, what this system needs to function is not something a GPS system can possibly provide. GPS knows how fast the aircraft is moving relative to the earth, but for flight envelope protection you need to know how fast the aircraft is moving relative to the surrounding air, which GPS doesn't have any way of knowing. The differences between these values is caused by wind and can be pretty large. It would be a recipe for disaster to let the computer limit what the pilot can do based on an arbitrary assumption that there's no wind. (And, as Terry comments, there's an additional difference caused by air pressure).
If I remember correctly, the AF 447 investigation concluded that the pitot tubes had thawed and began functioning properly well before impact; it was not the loss of airspeed indication that prevented the pilots from salvaging the situation. By this time the pilots were confused and thought the airspeed indication was still malfunctioning because it showed a much slower speed than they thought they ought to have -- whereas in fact it was working perfectly well.

On the other hand, one could theoretically mix in satellite weather and GPS-based altitude to get an idea of indicated airspeed. Though I don't know how accurate that satellite data is for wind speed at different altitudes.

@raptortech97: I don't think satellites have the foggiest idea about wind speeds and directions inside a thunderstorm.

@raptortech97 Satellite weather data doesn't directly provide wind information at all, let alone with enough accuracy to use for an aircraft's airspeed indication. You can get some idea of winds by seeing how fast the clouds are moving, but this is only helpful for determining averages over a large area, not for giving an accurate reading for a particular position/altitude combination. If we could get accurate wind information from satellites, Hurricane Hunters wouldn't exist.

Wind would cause true airspeed to differ from ground speed, but it is vital to know indicated airspeed, which you can get from true airspeed only by knowing the pressure altitude. Given an altitude from a GPS (if you can trust it) you could estimate pressure altitude, but with an error that depends (again) on current local atmospheric conditions. There may be additional complications I haven't mentioned. This makes for a very complex calculation with lots of opportunity for error.

@DavidK IIRC, airspeed is one of those nice things where people thought they should be measuring one thing (TAS) that was very hard to measure, but it turns out that the approximation that is easy to measure (IAS) is actually the more important number.

@cpast: Angle of attack would be even better.

@cpast Yes, that's the nice thing about a pitot tube (at least when it isn't iced over).

The short answer to this question is that commercial airliners do have GPS and they have for a long time. AF447 almost certainly would have been equipped with GPS. While what Terry said about the difference between airspeed and ground speed is very true, AF447 could have seen from their GPS unit that they were moving much slower than what they should have been.
Unfortunately, judging from the cockpit voice recorder transcripts, it seems that they were panicking and failing to think logically or communicate well with each other. It was almost entirely a case of pilot error, not lack of accurate information. The pilot in the right seat was almost continually pulling back on his side stick. This caused the aircraft to climb and bleed off airspeed until the wings stalled. Even after the aircraft entered a stall condition, the pilots never lowered the nose, which would have recovered from the stall. Instead, the pilot in the right seat actively held the nose high for the entire descent to the ocean.
Also, the pitot tubes thawed several minutes before the actual crash. All of the instrument indications were correct for quite a long time before the aircraft hit the ocean.
For more information on AF447, see Popular Mechanics' annotated cockpit voice recorder transcript of the incident.

Airliners do have GPS units. As the other answers and comments have indicated, GPS does not provide airspeed (or angle of attack) information.
It would seem reasonable to use the GPS as a backup in the following way: Under normal operation, the difference between TAS and the GPS estimate (allowing for some computational latency) should be fairly constant (the difference being the wind speed). When the difference exceeds some noise threshold for a period of time it issues a warning.
This wouldn't help in the case of Aeropero 603 but may have helped in the Air France 447 incident. (To clarify what I mean by help, I mean to reduce cockpit confusion.)
In the former case, a similar tracking system between the radar altimeter and the
barometric altimeter may have helped.

It's not clear how you think that would have helped AF 447. The flight computers did realize the airspeed indication was unreliable -- that's why they went into alternate law and disengaged the autopilot. From that instant onward, the pitot tubes were completely irrelevant to the accident sequence. The pilots were not prepared to be given manual control at that point in the flight, and in their confusion ended up flying the fully functional aircraft into a stall so it dropped into the sea.

Also, AF447 was flying through a thunderstorm at the time of the accident. Thunderstorms are characterized by strong turbulence, that is, dramatic local variation in wind speeds and directions, strong updrafts and downdrafts close to each other, etc. So your assumption that the wind velocity would be "fairly constant" wouldn't necessarily hold in those conditions anyway.

In addition to what @HenningMakholm said, pilots use indicated airspeed, not true airspeed. At the altitude airliners fly, the difference between true and indicated airspeed is very large because of the much lower atmospheric pressure at those altitudes.

It may have helped to have an unreliable airspeed indication which may have given the crew some idea of what was happening. This might have lessened their confusion. Knowing that the icing incident was over may also have helped.

Also, this does not actually answer the question that was posed. Answers on StackExchange sites should always answer the question. Please see [answer] for more information on how to write an answer on StackExchange.

@copper.hat I'm almost completely certain that the system did indicate both when the airspeed was not correct and also when its proper function was restored, but someone more familiar with flying Airbuses can correct me if I'm wrong here.

@copper.hat, repeat after me: The accident was not caused by the pilots lacking airspeed indications. It was not caused by the pilots being unaware that the pitot tubes had failed. The causal role of the failing airspeed indication was completely played out once it had caused the FBW computer to switch into alternate law and disengage the autopilot. From that point on the sole cause of the crash was the pilots' lack of familiarity with how the aircraft handled in cruise conditions under alternate law. Telling them anything about pitot tubes at that point wouldn't have helped the least.

The only thing that it could have saved the flight to tell the pilots was: "The controls are now in alternate law and will let you fly into a stall. Take care not to do that". Telling them that doesn't depend on having a fanciful backup airspeed determination system.

@HenningMakholm: There is no need to so patronising. I never suggested a cause, so I'm not sure why you are ordering me to repeat your words. The pilots do receive an indication that ALT1/2 are in effect. Knowing what triggered the degradation may have helped with their confusion.

@copper.hat: You suggested a cure, which only has a chance of being effective if one assumes a cause that the suggested cure would influence.

@HenningMakholm: Well, my take on reading the reports was that cockpit confusion was the issue. My suggestion above was a warning which may have helped reduce confusion. (My answer seems to have bothered you, and frankly I don't understand. If you have an issue with me, please write to me at joe.higgins@gmail.com and we can deal with it off this site. This exchange is tiresome.)

@copper.hat So am I. All I was saying is that 1) This post isn't an answer and 2) TAS doesn't really help you at 37,000 ft. and even less when they went over 40,000, where the flight envelope consists of a very narrow range of Mach numbers. Also, sorry for the canned [answer] comment. I just saw your rep on Aviation and didn't look at your rep on Math, so I thought you were a new user at first. I tend to post comments like that to help out new users.

@reirab: No problem at all.

authors: عبد الغفار كرفاع


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Why is the magnetic variation value from 1999, although the AIP Charts in my country are up to date?
Why is the magnetic variation value from 1999, although the AIP Charts in my country are up to date? In all of the chart examples I shared below, the variation value is 3.2°E and belongs to 1999. According to my research, the current variation value of ADANA LTAF airport is 5° 46' E. The year the charts are published is 2021. In addition, the variation value of 2017, 3.5°E, is shared on the airport chart. Why are all these values out of date and not fixed? Why is such a way of sharing followed in the charts? Any ideas?

Because the magnetic declination in a given area changes slowly over time, as little as 2–2.5 degrees every hundred years or so, or by 1 degree every three years in locations closer to the poles. Depends what part of the world the map covers. Not many airport facilities close to the poles.

The OP already knows that magnetic declination is changing with time. The question was about why the values on the charts are so old.

@Bianfable Read my answer again. The reason is because the declinations change very slowly over time. Values will not be updated for small fractions in changes.

First of all, thank you for your answer. I can understand why it's not on every amendment chart because it changes so slowly. But when the new magnetic deviation is 5° 46' E, why are they still sharing the 1999 value of 3.2°E instead of changing it in the newly published chart? There is not a small difference, but a big difference of almost 2.5 degrees. Isn't this ridiculous? Because we have new data and they prefer not to share it in the current chart (2021) (?). Interesting..

I suspect it's because few people are doing their navigation with methods that require taking deviations into account, and instead rely on GPS and other means of navigation data.


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What exactly is the interval and duration of occurrence represented by the acronym TEMPO?
What exactly is the interval and duration of occurrence represented by the acronym TEMPO? When we look at this How to interpret BECMG and TEMPO in TAF? question, we see the following in the answer statement: "The TEMPO group is used for any conditions in wind, visibility, weather, or sky condition which are expected to last for generally less than an hour at a time (occasional), and are expected to occur during less than half the time period." What exactly does this statement mean? For example, when we look at the expression "TEMPO 0414/0418 -SHRA", will the shower rain last 4/2=2 hours or 1 hour? I would be glad if you explain.

Weather is dynamic and it doesn't always go along with the weather report.
TEMPO 0414/0418 -SHRA

This indicates that between 14z and 18z there will be rain showers coming staying less than one hour and then leaving.
Will the actual weather always do that.  Nope.  Hence it is good to get an updated weather report when you can.

Then why is the phrase "and are expected to occur during less than half the time period" included in the definition? What is meant by this: Isn't it 2 hours, which is half of the 4-hour period?

@pilot162 It just means they expect rain for less than 2 hours during the 4-hour period, where each rain shower is expected to last less than 1 hour. The actual weather might differ, that's why civilian weather predictions typically just give a rain probability, you just don't know for sure...

Here is a real answer! Thank you.


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Which values do "PANS-OPS" and "Standard" labels represent in the minimum table seperately? (minimums, circle-to-land values, aircraft categories...)
What is the difference between these two labels and which values do they represent in the minimum table exactly? ("PANS-OPS" and "Standard") What are the values that Standard and PANS-OPS labels represent separately? (Minimums, visibility, categories). Apart from the fact that they represent different documents and sources, the important thing to me is: Which label provides a reference to which values in the table? Because when I look at the explanations, it is said that it is determined according to EASA AIR OPS for "Standard" and ICAO rules for PANS-OPS. Minimum values, visibility values, circle-to-land values, speed values, and aircraft categories... I want to know by which reference source they were all determined.

Is it possible for a published value to come from a particular source, yet also comply with another criteria?  (i.e. EASA comes up with the numbers, and ICAO approves of them...)

Actually, the indirect question here was why there are two labels. Having "Standard" and "PANS-OPS" makes it difficult and confusing for me to understand what they are referencing. But in conclusion, according to what you said, EASA determines the values and ICAO approves these values according to its own standards. Jeppesen also publishes it as a chart. I hope I am correct because I will accept this as the answer.

That seems to be what the published explanation says.


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Why is there no final approach fix symbol on some of the Jeppesen VOR charts? (Maltese Cross Symbol)
Why is there no final approach fix symbol on some of the Jeppesen VOR charts? (Maltese Cross Symbol) What does the box marked with a red arrow mean when there is no FAF symbol and how is it defined? Because sometimes it happens that "no FAF" is written in the box. If it doesn't say "no FAF" it means there is FAF but why is the FAF symbol not shown in the profile view?


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What is the distinct difference between "Std" and "Standard" markings on Jeppesen charts?
What is the difference between "Std" and "Standard" markings on Jeppesen charts? I read the descriptions, but I can't make a clear distinction. Because both EASA and ICAO represent similar things. Does what is written as Jeppesen Standard AOM mean State minimums? I would appreciate it if you could explain all of them in a simpler and clearer way.

Yes, EASA and ICAO are "similar", but they are also separate organizations with their own publications and standards.  Just like the FAA also has their own regulations that may be similar, yet different.
Each organization may have different methods or rules for determining approach minimums, and the definitions quoted in your question appear to be simply describing the source of the information that Jeppesen is publishing.


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Although the missed approach point in the profile view is 1.1 DME-400 feet, the GS out reference altitude is given as 410 feet in 1.0 DME. HOW?
Although the missed approach point in the profile view is 1.1 DME-400 feet, the GS out reference altitude is given as 410 feet in 1.0 DME. HOW?!

Based on GS out reference altitudes, we are expected to be at 410 feet at 1.0 DME. But if we look at the profile view, we see that the missed approach point corresponds to 400 feet at 1.1 DME. How is this possible?
If this is a mistake, I cannot understand how it was overlooked. But if there's a logical explanation, I'd like to know. Also, if there is an error, I would like to know which information is an error and which information is correct. I know the references given are approximate and I also know that the calculations don't quite match (slant range, shape of the earth, rounding the DME value to 1 decimal place, etc.). But there is a big mistake here.
I'm also sharing the entire Jeppesen chart page for clarity:

LTAF Adana International Airport Jeppesen chart page 21-1.

The descent angle is different: ILS 3°, LOC 3,08°.
So the altitudes will be different at the same DME distances.

What you said is correct, but the "missed approach point" is the point given according to the LOC descent angle (3.08 degrees) and in the profile view given as 400 feet at 1.1 DME. In addition, the IADA DME-Altitude chart given above also represents the LOC descent angle approach since it is GS out and says that we should be at 410 feet at 1.0 DME. So both things represent the LOC descent angle, while one gives 1.1 DME-400' and the other 1 DME-410'. @Jon


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How do I keep coordinated on a windy day?
I've noticed on windy days that keeping the aircraft coordinated can be difficult -- the ball will tend to bounce back and forth in the turn coordinator, and I will find myself "chasing" it with the rudder pedals.
Any advice for managing this situation?  At cruise it doesn't worry me as much as setting up for approach to land. I think I've read too many stall/spin in the pattern stories lately...

I've flown in some bumpy weather (VFR). My advice: don't chase any instruments! Just go with the flow... Literally

The ball in the turn coordinator is loose, and it wants to stay in the same place as an object at rest wants to stay at rest. When the ball seems to be bouncing around it's actually the airplane bouncing around it due to rough air rather than the aircraft being our of balance relative to the airflow.
When you saw at the rudder in rough air you are actually throwing the aircraft out of balance one way and then the other. You can end up over-controlling with coarse rudder inputs and possibly snap-rolling the airplane, although that's unlikely. More likely you will just tire yourself out and waste concentration.
Keep your feet nice and steady on the controls, there's rarely any need for large inputs. When the air is smooth have a glance at the ball and make corrections then. Keep your vision outside the cockpit as much as possible and keep your airspeed up.

In a steady wind, even in gusty conditions, the wind direction doesn't change much, except by a few degrees. Its enough to glance at the ball each time you enter a turn and each time you return to straight flight, and make a gentle correction.
Where things get tricky is when the winds are variable (METAR: 180V240 or VRB005KT), there's wind shear, or there's turbulence, in which case you will be working the stick as well as the rudder to keep the plane on course and coordinated.
You'd have to get the ball pretty far (at least one ball diameter) out of whack to be dangerous, but your back seat passengers will feel any lack of coordination.


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Is there a central database for all airline reservation information?
So we are flying on a reservation that flies from LAX to NRT with United then from NRT to BKK on Thai Airways via a United codeshare. This reservation was booked through United's website. When the reservation was confirmed, I noticed that the E-Ticket number was the same for all segments of the flight, across both United and Thai. Is there any central computer system used by airlines that keeps track of information such as these E-Ticket numbers to prevent discrepancies during ticketing? I ask this because I am very curious how exactly each airline's computer system "talks" to each other and if there is some sort of established protocol for doing so.

I'm voting to close this question as off-topic because it is more about Travel and travel reservation.

The simplest answer is that United and Thai have a codeshare arrangement, so United booked a ticket on all 4 segments using its own reservation system. United's reservation system communicated with Thai's to reserve your place, and the ticket was issued by United.
that being said, there are a number of GDSs (Global Distribution Systems), which are multi-airline reservation systems, all of which communicate with each other. Complete information on GDSs can be found in Wikipedia.

So in order for airlines to codeshare do they have to be part of the same GDS?

GDS? I love a good TLA.


text:
Where do websites like expertflyer.com get their information?
I've been looking at internet resources like expertflyer.com and KVSTool which query information like live seat maps, upgrade availability and fare bucket information. To my knowledge, this seemed like proprietary information unique to each individual airline. Is there a public API or database that these pieces of software are using or do they simply scrape the websites of each individual airline? Perhaps this might be a question better suited for Programming SE but I thought I'd start here.

The Open Data stack exchange site may have inputs here, since they tend to share info on what sources of data are available to the public.

Simply put, ExpertFlyer gets its data from purchasing it from the GDSs (global distribution systems for airlines) these are the same systems that travel agents (online and off) use to book tickets/travel for their customers. This has a cost but has advantages vs free but less reliable means of acquiring flight data.
Other services may screen scrape (take) information from public airline websites, however airlines frown upon that. We have seen active campaigns by airlines to go after services that collect data in this manor.
Please note, this post is not meant to be "promotional" however fully answering the question posed requires explaining how different services may acquire flight data. Also, if the name "ExpertFlyer Voice" didn't indicate to you, I am a representative of ExpertFlyer.com

Although the factual answer is in here, there's quite some promotionial content around it. As such, it might be flagged as spam and removed, please clean up your answer to include factual information only.

I don't see the promotional content.  As a developer the answer (unfortunately voted down) is quite useful and gives the information a developer would be interested in.

The first sentence is a good answer to the question. The rest is an explanation of why the service is better than other on the market, hence not necessary. Now the question itself doesn't seem to be on-scope here as it deals with travel reservation systems, rather than with aviation.

This a good answer but should have a clear disclaimer about your affiliation. I'd also lose the last sentence of the first paragraph


text:
Which "North degree" is using on the PFD heading, Jeppesen Charts and Maps? (Headind indicator, MSA, coordinate lines, bearings..) True or Magnetic?
I found out that "All charts are drawn in reference to true north". But if my heading indicator shows a magnetic heading on my flight display, how do I apply the true heading value on the charts using my magnetic heading in pdf when flying in IFR conditions? Also, I wonder about the MSA alignment on the chart which I posted. Usually, in MSA parts, the MSA is not aligned with the chart's longitudes and parallels. It's rotated slightly clockwise or counterclockwise. And finally, are the coordinate lines on the charts relative to true north or to magnetic north? They're all mixed up in my head, I'd appreciate it if you could help.

Magnetic North is generally used for a both aircraft navigation displays and chart representations.
Yes, it is correct that "All charts are drawn in reference to true north", but all headings and tracks are given as Magnetic.
The exception is aircraft and charts used in the high Arctic latitudes.
(generally north of 82N or south of 82S)

Most aircraft navigation displays are designed to display magnetic north. (some aircraft can select between Magnetic North and True North).
MSA charts are rotated to orient to Magnetic North, but so is the rest of the chart.
The Lat/Long coordinate lines are oriented to True North because they don’t represent headings or tracks.
Some charts used in the far north will use True North headings and tracks, but they will include “T” as in “359T”.
So, when using your chart, just follow the magnetic headings or tracks and as written, and disregard the orientation of the chart.

Are the MSA sections based off a VOR referenced to current magnetic North or to the VOR radials, which used magnetic North when the VOR was built (or last adjusted)?

@Mike Sowsun thank you so much sir, much obliged.

@Bianfable I don’t know, but I would think that any differences would be negligible.

@MikeSowsun Well that would depend on the VOR. For most it's probably insignificant, but for some VORs the difference can be quite large. Anyway, I looked at the Jeppesen chart legend and it says "Sector defining radial/bearing", which to me sounds like they are using VOR radials (if it is based off a VOR, else bearing to fix).

@Bianfable If they’re shown as radials off a VOR, they’ll be from whenever that VOR was last calibrated, so use the CDI.  If they’re just headings, use the compass.


text:
What is really meant by max 240 kt, 220 kt and 185 kt in the picture of Jeppesen chart?
What is really meant by max 240 kt, 220 kt and 185 kt in the picture of Jeppesen chart? What I don't understand is: are the speed limits for waypoints or for routes between waypoints. If speed restrictions mean routes between waypoints, do they cover before or after the waypoint? I will leave two examples below, one is STAR and one is SID chart.
For example at the STAR chart, is it possible to increase our speed above 240kt after CRL VOR and then reduce our speed to 220kt again at BU214 waypoint after crossing BU211 BU212 BU213 waypoints respectively?

Another example is from the SID chart: Does the speed limit for point BU710 cover the route to BU710 after takeoff? Or just the BU710 point? Or BU710 point and beyond?

The speeds are charted at waypoints and they apply when you cross that waypoint. On a departure, the restriction applies until crossing the waypoint but no longer applies afterwards - though another restriction at a later waypoint would apply. On an arrival, the reverse is true: fly whatever speed until the first restriction, then comply with that at & after the point.
The typical phrasing on US departure procedures is "do not exceed XXX knots until past YYYYY waypoint" - which rules out speeding up & then slowing down just for the waypoint. The reason behind this is that ATC wants to control the flow & separation of aircraft, and points provide "gates" to do that: everybody holds (no more than) 220 knots until "here", then (no more than) 240 knots until "here", and then normal climb speed after that.
The same logic applies on arrivals, with the defined points as places where the flow of traffic slows down in a uniform, predictable manner.
The general practice (which may or may not be codified in a given AIP or SOP) is that you want to get fast as soon as allowed (i.e. on departures), and stay as fast as possible for as long as allowed (on arrivals). So, on the top chart, you'd expect to slow to 240 so as to cross CRL at that speed, but no earlier. Then start slowing about 2 miles prior to BU214 so as cross it at 220, having held 240 until then. Sometimes it's necessary to slow sooner than this & be below the published maximum speeds in order to comply with subsequent restrictions - and that's fine since they're max speeds, not "at" speeds. But the most general case is that you'll get fast as quickly as allowed & stay fast as long as allowed. But not in a manner where you slow back down on a departure, nor speed back up on an arrival - unless the controller clears you for it (which is pretty uncommon).

The Jeppesen Charts legend does not go into any detail about these restrictions. It says in general:

SPEED RESTRICTIONS
Speed restrictions that apply to the entire procedure are shown below the procedure title.

Speed restrictions vary widely within individual procedures. They can be in the tabulated text, boxed, and/or
placed in information boxes at the associated track, fix or phase of flight.

The exact rules may vary by country. It is my understanding that the constraint is valid until reaching that waypoint on a SID and after reaching it on a STAR.
This is also confirmed by the US AIM:

5-2-9. h. 2. Pilots should not exceed a published speed restriction associated with a SID waypoint until passing that waypoint.
5-4-1. a. 1. STAR procedures may have mandatory speeds and/or crossing altitudes published. [...] Pilots should plan to cross waypoints with a published speed restriction, at the published speed, and should not exceed this speed past the associated waypoint unless authorized by ATC or a published note to do so.

(emphasis mine)


text:
Which of the arrows in the magnetic variation symbol represents which North value (Magnetic N, True N)?
Which of the arrows in the magnetic variation symbol represents which North value (Magnetic N, True N)? According to my calculations, the arrow pointing to the top should point to magnetic north, perpendicular to the page. But I am not sure.

Related: Are Jeppesen Approach, SID charts in Magnetic North or True North?

You say "according to my calculations" - what calculations did you make? As it stands the question is essentially a duplicate of the link @Bianfable posted, but if you explain your thinking you might get a more interesting answer tailored to your understanding.

To find magnetic north, variation is added or subtracted from true north. If the variation is eastward, you subtract the variation from true north to find magnetic north. But if the variation is west, you add variation to true north to get magnetic north...

...If the variation is west, the direction of increase will always be clockwise on the 360-degree dial, so the true north arrow will be to the left of the magnetic north arrow. But if the variation is east, the direction of decrease will always be counterclockwise on the 360-degree dial, so the true north arrow will stay to the right of the magnetic north arrow. I hope you have the ability to perceive what I mean.

The chart is always drawn with true north pointing straight up. The magnetic variation is given on the arrow pointing along the local direction of the field lines (not technically towards magnetic north). So 10°W means the local field lines are 10° to the West of true north.
You said in the comments

To find magnetic north, variation is added or subtracted from true north. If the variation is eastward, you subtract the variation from true north to find magnetic north. But if the variation is west, you add variation to true north to get magnetic north.

This is not quite correct. This rule applies to a heading or course, not the direction of true/magnetic north. Consider this picture:

We have 10°W variation, so we have to add the variation to the true heading to get the magnetic heading:
$$ \color{green}{\text{true heading}} + \text{variation} = \color{red}{\text{magnetic heading}} $$
$$ \color{green}{30^\circ} + 10^\circ = \color{red}{40^\circ} $$
Therefore, your pictures are perfectly consistent with this rule (if applied to a heading or course).


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What is the change of "Airspace" here? Does it mean the airspace class of the airport has changed?
What is the change of "Airspace" here? Does it mean the airspace class of the airport has changed? I haven't reached a source where I can find the airspace classes used in my country anyway (Turkey). If what is meant in this question is airspace class, I will be more confused because there is no symbol or text indicating this on Jeppesen charts. If the expression "airspace" mentioned here has a different meaning, what is it? This screenshot is taken from LTBU airport's 11-1 page ILS Z or LOC Z Rwy 04 Jeppesen chart, revision date is 22 OCT 21 and the effective date is 4th of Nov.

I recommend you find a copy of the previous revision and see what actually changed.  It's probably either the airspace classification or the boundaries of the airspace itself, but without directly comparing the two you can only speculate as to what may have changed.  As it stands there isn't enough context to answer the question.

A very sensible approach. I absolutely agree with what you said, if I can understand the difference after comparing it with the previous chart, I will share the answer here. Thanks again..

When we examine the 11-1 page of the previously printed chart for LTBU airport, we can clearly understand what the mentioned changes mean. The change we call "Procedure Title" is changing the name of the chart from "ILS Z Rwy 04" to "ILS Z or LOC Z Rwy 04". The meaning of the change indicated by the word "Airspace" is the restricted airspace with the code "LT(R)-40" added to the southeast of the airport. I am sharing the sections of the two charts so that you can understand the difference. Many thanks to Michael Hall for guiding me to find the answer.